768 CAMBRIAN BRACHIOPODA. 



transversely oval in outline, with straight hinge edge, corresponding to the greatest hreadth of the shell. The ventral 

 valve is moderately arched, the dorsal somewhat less. The surface of both valves is covered with comparatively 

 strong ribs, arranged in bundles. On the middle of the ventral valve there is an especially well-marked rib or bundle 

 of ribs. Corresponding to this on the dorsal valve there is a well-marked sinus, limited on each side by a strong bundle 

 of ribs. 



t'he form just described agrees in the main so well with the figures given by Salter and Davidson of the small 

 English form identified with Wahlenberg's lenticularis that I can hardly doubt its specific identity with the latter. 



Of Orthis sp. Kayser remarks [1876, p. 9]: 



Before me lies a cast from Tilcuya, representing a third Orthis species. It is almost equal in size to 0. saltensis, 

 but differs from it in outline, which is greatly prolonged transversely, the greatest breadth at the hinge edge, and the 

 feeble winglike projection of the hinge corners. This last-named characteristic and the much larger dimensions also 

 distinguish this fossil from 0. lenticularis. The surface of the shell has been covered with very strong bundles of ribs. 



Matthew [1892, pp. 48-49] has named three varieties of Orusia lenticularis. I fiiid essen- 

 tially the same forms in the collections from Sweden and Newfoundland. Two of the varieties, 

 Orusia lenticularis atrypoides and 0. lenticularis lyncioides, have been illustrated in this mono- 

 graph from Matthew's type specimens. The third variety, Orusia lenticularis stropTiomenoides, 

 occurs associated with specimens of Orusia lenticularis in the Swedish material, and does not 

 appear to be of varietal value. It is illustrated in this monograph by Plate XCVIII, figures 

 Ic and 2b. 



FoKjiATioN AND LOCALITY. — TTpper Cambrian: (9f) Limestones of the Olenus zone at Noersnses, west of Chris- 

 tiania; (3231) with Parabolina spinulosa at Toien, about 1 mile (1.6 km.) northeast of Christiania; (323m) Etage 2b 

 at Oslo, about 1 mile (1.6 km.) southeast of Christiania; (323n [Brogger, 1882, p. 48]) Etage 2b at Vestfossen, 10 miles 

 (16.1 km.) west-southwest of Christiania; (323o) « Etage 2b, in the city of Christiania; (323p) Etage 2b at Slemmestad, 

 about 3 miles (4.8 km.) southwest of Christiania; (323(j. [Brogger, 1882, p. 101]) Etage 2b at Kartveit, in the 

 Christiania region; (323r) <i Etage 2b at Krekling, in Sandsvar; (323s) « Etage 2b at Gjogrefos, in Sandsvar; (323t) 

 Etage 2b in Hedemarken, east of Lake Mjosen (Miosen), about 40 miles (64 km.) north-northeast of Christiania; (323u) " 

 !l6tage 2b at'Oxna (Oksna), valley of Glommen River; and (323v [Davidson, 1869, p. 231]) at Egeherg (about 1.5 

 miles (2.4 km.) southeast of Christiana?); all in Norway. 



(310a) Shales of Olenus Iruncalus zone, Oeland Island; (390n) limestones of Olenus zone at Hunneberg, western 

 boundary of the Province of Skaraborg; (309m) limestones forming 3c of the Olenus series atAlunbruk (alum works), 

 southern part of Oeland Island; (390o) arenaceous shales at Andrarum, 20 miles (32 km.) northwest of Simrishamn, 

 Province of Christianstad ; and (390p [Davidson, 1869, p. 231]) at Kinnekulle, northeast of Lidkoping, Province of 

 Skaraborg; all in Sweden. 



Drift bowlders of gray bituminous limestone at the following localities [Roemer, 1885, pp. 33 and 34]; (386e) 

 Between Vistula and Elbe rivers, in Schleswig-Holstein and Mecklenburg-Schwerin; (386f) near Wismar, Mecklen- 

 burg-Schwerin; (386g) near Rostock, Mecklenburg-Schwerin; and (386h) near Meseritz, Province of Posen; all in 

 Germany. 



Upper Lingula flags at the following localities: (318s) & Ogof-ddu Cliff, Carnarvonshne; (366s) 5 miles (8 km.) 

 east of Ffestiniog, Merionethshire; (318t) 6 Penmorfa Church, Tremadoc, Carnarvonshue ; (318u) 6 Gwerny-y-Barcud; 

 (318v)6 Rhiwfelyn; (318) & Penmain Pool, west of Dolgelly, Merionethshire; (318a) 6 Criccieth, Carnarvonshire; and 

 (318b [Davidson, 1869, p. 232]), near Portmadoc, Carnarvonshire; all in North Wales. 



(3) Shaly limestone 300 feet (91.4 m.) above the Paradoxides zone; and (6v) shaly limestones 325 feet C99.1 m.) 

 above the Middle Cambrian; both on Manuels Brook, Conception Bay, Newfoundland. 



(314i) Shale picked up on beach in Smith Sound, Trinity Bay, Newfoundland. 



(lOh) Shale on small east branch of Barachois River, 0.75 mile (1.2 km.) north of the crossroad from Boisdale 

 to Upper Leitches Creek; (13q.) shales of the Bretonian division of Matthew's [1903, p. 45] section on Gillis Brook, 

 East Bay; (307h) c in Division C3b? (possibly C3e) of Matthew's section, on McLeod Brook=Barachois River; (307i) c 

 in Division C3b of Matthew's section on McNeil Brook, east of Mira River; (307]) « limestone in Division C3b? (pos- 

 sibly C3c) on East Bay, east of Bras d'Or Lake; and (307 1) = limestone in Division C3b? (possibly C3c) on Gillis Brook; 

 all in eastern Cape Breton, Nova Scotia. 



Limestone lentils in black shales of Division C3a of Matthew's section at the following localities: (308b [Mat- 

 thew, 1892, p. 48]) on Germaine Street, St. John; and (308f) " on King Street, St. John; both in St. John County, New 

 Brunswick. 



(389b [Kayser, 1876, p. 9]) Sandstone at Tilcuya, Province of Jujuy, Argentina, South America. 



Middle Cambrian : (55b) Top of the Eldorado limestone [Walcott, 1908f, p. 184], west side of Secret Canyon, 

 Eureka district [Hague, 1892, Atlas], Eiu-eka County, Nevada. 



(320f) Limestone at Andrarum, 20 miles (32 km.) northwest of Simrishamn, Province of Christianstad, Sweden. 



a Brogger, 1882, p. 4. 6 Davidson, 1868, p. 314. c Matthew, 1903, p. 210. 



